Investment Partnership (Summary of Equity Method Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Total assets	$ 763,870	$ 668,020
Leigh Valley Associates, LP
Schedule of Equity Method Investments [Line Items]
Total assets	43,850	49,264	$ 49,919
Mortgage payable	199,451	126,520	128,883
Revenue	34,945	36,923	36,497
Property operating expenses	9,038	8,659	9,599
Interest expense	10,907	7,570	7,708
Net income	11,389	17,264	15,844
PREIT’s share of equity in income of partnership	$ 5,695	$ 8,632	$ 7,922